Buggy code:
public class CharSequenceInputStreamTest { private static final String ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" ; private static final String LARGE_TEST_STRING ; private static final String TEST_STRING = "à<seq2seq4repair_space>peine<seq2seq4repair_space>arrivés<seq2seq4repair_space>nous<seq2seq4repair_space>entrâmes<seq2seq4repair_space>dans<seq2seq4repair_space>sa<seq2seq4repair_space>chambre" ; private final Random random = new Random ( ) ; private Set < String > getRequiredCharsetNames ( ) { } private void testBufferedRead ( final String testString , final String charsetName ) throws IOException { } @ Ignore @ Test public void testBufferedRead_AvailableCharset ( ) throws IOException { } @ Test public void testBufferedRead_RequiredCharset ( ) throws IOException { } @ Test public void testBufferedRead_UTF8 ( ) throws IOException { } private void testCharsetMismatchInfiniteLoop ( final String csName ) throws IOException { } @ Test public void testCharsetMismatchInfiniteLoop_RequiredCharsets ( ) throws IOException { } private void testIO_356 ( final int bufferSize , final int dataSize , final int readFirst , final String csName ) throws Exception { } @ Test public void testIO_356_B10_D10_S0_UTF16 ( ) throws Exception { } @ Test public void testIO_356_B10_D10_S0_UTF8 ( ) throws Exception { } @ Test @ Ignore public void testIO_356_B10_D10_S1_UTF8 ( ) throws Exception { } @ Test @ Ignore public void testIO_356_B10_D10_S2_UTF8 ( ) throws Exception { } @ Test public void testIO_356_B10_D13_S0_UTF8 ( ) throws Exception { } @ Test @ Ignore public void testIO_356_B10_D13_S1_UTF8 ( ) throws Exception { } @ Test public void testIO_356_B10_D20_S0_UTF8 ( ) throws Exception { } private void testIO_356_Loop ( final String csName , final int maxBytesPerChar ) throws Exception { } @ Test public void testIO_356_Loop_UTF16 ( ) throws Exception { } @ Test public void testIO_356_Loop_UTF8 ( ) throws Exception { } @ Test public void testLargeBufferedRead_RequiredCharsets ( ) throws IOException { } @ Test public void testLargeBufferedRead_UTF8 ( ) throws IOException { } @ Test public void testLargeSingleByteRead_RequiredCharsets ( ) throws IOException { } @ Test public void testLargeSingleByteRead_UTF8 ( ) throws IOException { } private void testMarkReset ( final String csName ) throws Exception { final InputStream r = new CharSequenceInputStream ( "test" , csName ) ; try { <START_BUG> r . skip ( 2 ) ; <END_BUG> r . mark ( 0 ) ; assertEquals ( csName , 's' , r . read ( ) ) ; assertEquals ( csName , 't' , r . read ( ) ) ; assertEquals ( csName , ( - 1 ) , r . read ( ) ) ; r . reset ( ) ; assertEquals ( csName , 's' , r . read ( ) ) ; assertEquals ( csName , 't' , r . read ( ) ) ; assertEquals ( csName , ( - 1 ) , r . read ( ) ) ; r . reset ( ) ; r . reset ( ) ; } finally { r . close ( ) ; } } @ Test @ Ignore public void testMarkReset_RequiredCharsets ( ) throws Exception { } @ Test public void testMarkReset_USASCII ( ) throws Exception { } @ Test public void testMarkReset_UTF8 ( ) throws Exception { } @ Test public void testMarkSupported ( ) throws Exception { } private void testReadZero ( final String csName ) throws Exception { } @ Test public void testReadZero_EmptyString ( ) throws Exception { } @ Test public void testReadZero_RequiredCharsets ( ) throws Exception { } private void testSingleByteRead ( final String testString , final String charsetName ) throws IOException { } @ Test public void testSingleByteRead_RequiredCharsets ( ) throws IOException { } @ Test public void testSingleByteRead_UTF16 ( ) throws IOException { } @ Test public void testSingleByteRead_UTF8 ( ) throws IOException { } private void testSkip ( final String csName ) throws Exception { } @ Test @ Ignore public void testSkip_RequiredCharsets ( ) throws Exception { } @ Test public void testSkip_USASCII ( ) throws Exception { } @ Test public void testSkip_UTF8 ( ) throws Exception { } private int checkAvail ( InputStream is , int min ) throws Exception { } private void testAvailableSkip ( final String csName ) throws Exception { } private void testAvailableRead ( final String csName ) throws Exception { } @ Test public void testAvailable ( ) throws Exception { } }

Fix:
assertEquals ( 2 , r . skip ( 2 ) ) ;